Validation of Pulse Oximetry During Progressive Normobaric Hypoxia Utilizing a Portable Chamber

Validation of pulse oximetry in commercially available normobaric hypoxic chambers (NHC) has not been previously reported. The present study examined the validity of pulse oximetry (SpO2) against direct measurements of arterial oxygen saturation (SaO2) via co-oximetry (AVOXimeter 4000) in 13 young adults age 21.3 ± 0.6 years. Over a period of 2.5 hrs, the inspired fraction of oxygen inside a NHC (Hypoxico, Inc.) was progressively reduced from 20.9% to 11.5%. Measurements of SaO2 at baseline and at 15, 30, 60, 90, 120, and 150 min during the hypoxic exposures were compared with SpO2 estimates of oxygen saturation (Nellcor 295) using reflectance (RS-10, temporal) and transmission (D-25, finger) sensors. Regression analysis and methods for assessing agreement (bias, b; precision, p) of SaO2 with SpO2 were similar (R2 = 0.92, 0.89; b = 0.016, −0.47; p = 2.47, 3.03; RS-10 and D-25, respectively). When SaO2 < 85%, RS-10 had greater validity than D-25 (R2 = 0.73, 0.56; b = 1.38, 1.13; p = 2.72, 4.34; RS-10 and D-25, respectively). In light of these findings, caution should be exercised when monitoring individuals with pulse oximetry during desaturation episodes below 85%. When employing frequent NHC exposures, a priori validation of SpO2 utilized to assess blood oxygen status appears warranted. Key words: oxygen saturation, co-oximetry, altitude

The effect of feed deprivation on gastrointestinal respiration and Na+, K+-ATPase in chicks

In order to investigate the effect of nutrient availability on energy metabolism of the gastrointestinal tract (GIT) of chicks, two experiments were conducted. In exp. 1, jejunal slices from male White Leghorn chicks at 14 d were incubated in salt-based balanced medium (SBM) or complex medium (CM) for 30 min. The total O2 (TO2) and ouabain-sensitive O2 (OSO2) consumption in jejunal slices were significantly decreased in SBM. The results from exp. 1 imply that when the GIT mucosa is subjected to nutrient deprivation, the utilization of oxygen consumption is altered primarily by shifting active Na+ pump activity. Changes in the TO2, OSO2 and amiloride-sensitive O2 (ASO2) uptake in response to feed deprivation in the small intestine of male White Leghorn chicks were investigated in exp. 2. There was little change in TO2, OSO2 and ASO2 per unit of dry matter of the small intestine from birds subjected to fasting, except for a TO2 decrease in the jejunum of 48 h fasted chicks. However, there were significant reductions in TO2, OSO2 and ASO2 in the jejunum when data were expressed per unit DNA. Na+, K+-ATPase-dependent respiration represented 31–37% of TO2 in the avian jejunoileum. Amiloride-sensitive respiration accounted for 10–18% of TO2 in the jejunoileum. The maximal amount of 3Houabain binding sites of jejunal enterocytes was significantly decreased in chicks fasted for 48 h (P < 0.05). Key words: Oxygen consumption, fasting, Na+, K+-ATPase, ouabain, jejunum, ileum, chicks

Reliability and Validity of a Portable Metabolic Measurement System

The purpose of this study was to assess the reliability and validity of a portable metabolic system (TEEM 100) during submaximal and maximal [Formula: see text] exercise using a computer-based metabolic system as the reference system (REF). Between repeated trials of submaximal exercise at three constant loads, differences in ventilation [Formula: see text] and oxygen consumption [Formula: see text] were 0.2 ± 4.9 L∙min−1 and 0.03 ± 0.10 L∙min−1 for REF, and 1.9 ± 0.7 L∙min−1 and 0.00 ± 0.17 L∙min−1 for TEEM 100. Pooled intraclass reliability coefficients for [Formula: see text] and [Formula: see text] calculated from the repeated submaximal trials were r =.89 and r =.94 for REF, and r =.86 and r =.94 for the TEEM 100. Respiratory exchange ratio (RER) measured by the TEEM 100 was significantly higher (p =.01) at only the lowest workload. At [Formula: see text], the TEEM 100 recorded significantly higher values for FeO2 (p =.01) and RER (p <.001). These results suggest that the TEEM 100 provides reliable and valid measurements of [Formula: see text] during submaximal and maximal exercise. Key words: oxygen consumption, indirect calorimetry, portable analysis, exercise, metabolism

Inhibition of oxygen evolution by ivalin

The inhibition of ATP synthesis, proton uptake, and electron transport (basal, phosphorylating, and uncoupled) from water to methylviologen by ivalin (a naturally occurring sesquiterpene lactone in Zaluzania triloba and Iva microcephala) indicates that it acts as electron transport inhibitor. Since photosystem I and electron transport from DPC to QA were not affected, while the electron flow of uncoupled photosystem II from H2O to DAD and from water to silicomolybdate was inhibited, we concluded that the site of inhibition of ivalin is located at the oxygen evolution level. Key words: oxygen evolution, ivalin, photosynthesis, sesquiterpene lactone.

Effects of Ir, Sn and Sb in the intermediate Ir1-x-y SnxSbyO2+0.5y layer of Mn-Mo-Sn-O electrocatalyst for hydrogen production

An attempt is made to reduce the use of IrO2 by the IrO2-SnO2-Sb2O5 intermediate layer which is necessary to avoid the growth of insulating titanium oxide on the titanium substrate for oxygen evolution ã-MnO2 type nanocrystalline Mn-Mo-Sn-O/Ir1-x-ySnxSbyO2+0.5y/Ti anodes in 0.5 M NaCl solution of pH 1 at 25°C. These electrodeposited Mn-Mo-Sn-based triple oxide anodes showed about 97.2-98.6 % oxygen evolution efficiency at high current density of 1000 A.m-2 in 0.5 M NaCl solution of pH 1 at 25°C. The high oxygen evolution efficiency of these triple oxide electrocatalysts maintained during prolonged electrolysis and even after the electrolysis for about two months. Key-words: Oxygen evolution efficiency; electrocatalyst; seawater electrolysis; CO2 recycling; XRD DOI: 10.3126/botor.v7i0.4387Botanica Orientalis - Journal of Plant Science (2010) 7: 79-84

Monitoring of Oxygen in Neonate: An Important Issue

Key words: Oxygen saturation; monitoring; neonateDOI: 10.3329/jcmcta.v21i2.7735 Journal of Chittagong Medical College Teachers' Association 2010: 21(2):30-34